Solar Energy, Vol.186, 328-334, 2019
Modeling of InGaP/InGaAs-GaAsP/Ge multiple quantum well solar cell to improve efficiency for space applications
Multiple quantum wells (MQWs) are incorporated in the current limiting middle subcell of standard InGaP/InGaAs/Ge multi junction solar cell (MJSC). Considering a realistic radiation dose in geo-stationary orbits (1 MeV electron irradiation-1 x 10(16) cm(-2) fluence), carrier lifetime is calculated and defined in the top cell and middle subcell region. The thermionic emission and recombination lifetimes are taken into consideration while defining lifetime in the middle MQW region. The physical thickness of quantum well (QW) and quantum barrier (QB) are slightly adjusted to numerically satisfy the strain balancing condition and to achieve higher efficiency at 1-sun (AMO spectrum). In addition to interface recombination, carrier removal effects were taken into consideration by changing the intrinsic region in the PiN middle subcell into n-type. With the nonidealities taken into consideration, the proposed device exhibits an efficiency of 32% at 1-sun AMO radiation and a peak efficiency of 37.63% at concentrated sunlight. Trap concentration of 1 x 10(17) cm(-3) in top cell with 10 ns lifetime defined in the middle cell emitter, base and MQW region is obtained as threshold point beyond which the device exhibits significant degradation.
Keywords:Multiple quantum well solar cells;Deep level traps;Carrier removal;Escape lifetime;Semiconductor device modeling